Soft thin laminated substrate

ABSTRACT

A soft thin laminated substrate including a plastic substrate, an alloy copper layer overlaid on the plastic substrate and a copper foil overlaid on the alloy copper layer. The alloy copper layer is an alloy of copper metal and at least one of nickel, chromium, manganese, molybdenum, iron and phosphorus. The alloy copper layer serves as a tie-coating of the copper foil, whereby the copper foil can tightly attach to the alloy copper layer to associate with the plastic substrate and form the soft thin laminated substrate.

BACKGROUND OF THE INVENTION

The present rehabilitation invention is related to a soft circuitsubstrate, and more particularly to a soft thin laminated substrateincluding one single alloy copper layer as the tie-coating of the copperfoil.

A conventional soft circuit substrate is composed of a soft substrateand a conductive copper foil associated with the substrate. Inconventional measure, the copper foil is adhered to the substrate bymeans of an adhesive. However, such measure often leads to problems ofdetachment, halogen flameproof agent, etc. In another traditionalmeasure, a liquid plastic resin is directly painted over the copper foiland the substrate. After dried and solidified, the copper foil isintegrally associated with the substrate. However, the above twomeasures can be hardly applied to those copper foils under 8 um. Inaddition, the adhesion force of the plastic resin between the copperfoil and the substrate is insufficient. That is, when the copper foilconducts current, a temperature (generally below 150° C. ) will more orless rise. Moreover, the material of the copper foil is different fromplastic resin. Accordingly, the thermal strain (mechanical tension ) ofthe copper foil is different from that of the plastic resin under suchtemperature. As a result, blister or lifting or peeling of the coatingof the soft circuit substrate will take place.

Recently, sputtering technique has been applied to manufacturing of softcircuit substrate. For example, Taiwanese Patent Publication No. 519860discloses a method for manufacturing soft circuit substrate and aproduct thereof.

FIGS. 3 and 4 show the soft circuit substrate structure of the abovePatent. The soft circuit substrate structure includes a polymer film 81,a chromium (Ni or Cr/Ni ) attaching layer 82 overlaid on one face of thepolymer film, a nickel-chromium alloy attaching layer 83 overlaid on oneface of the chromium attaching layer distal from the polymer film and acopper attaching layer 84 overlaid on one face of the nickel-chromiumalloy attaching layer distal from the chromium attaching layer. A copperfoil 85 is further deposited on the copper attaching layer.

In the above soft circuit substrate structure, the chromium attachinglayer, nickel-chromium alloy attaching layer and copper attaching layerall serve as tie-coatings of the copper foil. By means of thetie-coating, the polymer film with quite different physical propertiescan be tightly bonded with the copper foil.

However, in the above structure, the multiple tie-coatings lead toincrement of manufacturing time and complicate the manufacturingprocedure. As a result, the manufacturing cost is much higher. Moreover,the tie-coatings will increase the impedance of the material. Forexample, the impedance of chromium is more than ten times the impedanceof copper and the impedance of nickel is more than four times theimpedance of copper. All the above problems should be solved.

SUMMARY OF THE INVENTION

It is therefore a primary object of the present invention to provide asoft thin laminated substrate in which only an alloy copper layer isdisposed between the plastic substrate and the copper foil as thetie-coating of the copper foil. The copper foil can tightly attach tothe alloy copper layer to tightly associate with the plastic substrate.When the temperature rises, the coating will not blister or peel.Therefore, the using life is prolonged. Also, the cost is reduced andthe manufacturing procedure is simplified.

According to the above object, the soft thin laminated substrateincludes: a plastic substrate; an alloy copper layer overlaid on theplastic substrate, the alloy copper layer having a thickness within10˜10000 angstroms, the alloy copper layer being an alloy of 0.1%˜99.95%copper metal and at least one of nickel, chromium, manganese,molybdenum, iron and phosphorus; and a copper foil overlaid on the alloycopper layer.

The present invention can be best understood through the followingdescription and accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing the structure of the presentinvention;

FIG. 2 is a sectional view showing the structure of the presentinvention;

FIG. 3 is a schematic diagram showing the structure of a conventionalsoft circuit substrate; and

FIG. 4 is a sectional view showing the structure of the conventionalsoft circuit substrate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIG. 1. The soft thin laminated substrate of the presentinvention includes a plastic substrate 1, an alloy copper layer 2overlaid on the plastic substrate 1 and a copper foil 3 overlaid on thealloy copper layer 2.

The plastic substrate 1 can be made of one of polyimide (PI ), PET, PC,PMMA, etc. With polyimide exemplified, such material has excellentelectrical properties, anti-chemical properties and highest heatresistance among polymer materials. Therefore, the thermal strain can beminimized.

The alloy copper layer 2 is disposed on the plastic substrate 1 by wayof vacuum physical coating. The thickness of the alloy copper layer 2 iswithin 10˜10000 angstroms. The alloy copper layer 2 is an alloy of0.1%-99.95% copper metal and at least one of nickel, chromium,manganese, molybdenum, iron and phosphorus. The added metal hasexcellent electric conductivity. Preferably, the added metal will notincrease the impedance of the alloy copper layer 2.

The copper foil 3 disposed on the alloy copper layer 2 by way of vacuumphysical coating is composed of 10%-99.95% copper metal and at least oneof nickel, chromium, manganese, molybdenum, iron and phosphorus.

The vacuum physical coating can be thermal evaporation, electron beamevaporation, DC magnetron sputter, RF magnetron sputter, ion beamsputter, molecular beam epitaxy (MBE ) or plasma enhanced CVD. The alloycopper layer 2 of the present invention contains pure copper molecules.By means of the better electric conductivity of pure copper molecules,the bonding strength of the copper foil 3 can be enhanced. Moreover, bymeans of those low-impedance materials such as nickel, chromium,manganese, molybdenum, iron and phosphorus, the electric conductivity ofthe alloy copper layer 2 will not be greatly reduced.

In the soft thin laminated substrate structure of the present invention,the alloy copper layer 2 serves as a tie-coating of the copper foil 3.The alloy materials of nickel, chromium, manganese, molybdenum, iron andphosphorus in the alloy copper layer 2 have better bonding strength toplastic material so that the alloy copper layer 2 can be more firmlybonded with the substrate 1. Also, the copper foil 3 can tightly attachto the alloy copper layer 2 to associate with the plastic substrate 1.It is known from an actual pull test, the peel strength of the soft thinlaminated substrate of the present invention is up to 0.65 kg/cm².Accordingly, the structure of the present invention can truly well bondthe plastic substrate 1, alloy copper layer 2 and copper foil 3 witheach other. Moreover, the plastic substrate 1 of the present inventionhas better thermal strain and the plastic substrate 1, the alloy copperlayer 2 and the copper foil 3 are better bonded with each other.Therefore, when the temperature rises to 150° C., the coating of thepresent invention is uneasy to blister or lift or peel. Therefore, theusing life of the present invention is prolonged.

In conventional technique, the tie-coating is formed of a three-layerstructure, that is, a chromium attaching layer, a nickel-chromium alloyattaching layer and a copper attaching layer. In comparison with theprior art, the soft thin laminated substrate structure of the presentinvention only includes an alloy copper layer as the tie-coating fortightly bonding the plastic substrate 1, alloy copper layer 2 and copperfoil 3 with each other. Therefore, the present invention can achievedouble effects of decrement of cost and simplification of manufacturingprocedure.

The above embodiments are only used to illustrate the present invention,not intended to limit the scope thereof. Many modifications of the aboveembodiments can be made without departing from the spirit of the presentinvention.

1. A polymeric substrate comprising: a plastic substrate; an alloycopper layer overlaid on the plastic substrate, the alloy copper layerbeing disposed on the plastic substrate by way of vacuum physicalcoating, the alloy copper layer having a thickness within 10˜10000angstroms, the alloy copper layer being an alloy containing copper metalranging from 0.1 to 99.95 weight % in said alloy and at least one ofmanganese, molybdenum, and phosphorus; and a copper foil overlaid on thealloy copper layer by vacuum physical coating.
 2. The polymericsubstrate as claimed in claim 1, wherein the copper foil is composed ofcopper metal ranging from 10 to 99.95 weight % and at least one ofmaterials from the group of materials consisting of nickel, chromium,manganese, molybdenum, and phosphorus.
 3. The polymeric substrate asclaimed in claim 1, wherein the plastic substrate is made of a materialfrom the group of materials consisting of PI, PET, PC and PMMA.